Method of preparing polymer coated-wax impregnated cellulosic stock

ABSTRACT

Porous cellulosic stock can be coated with a thermoplastic polymer coating while being impregnated with a wax by this invention. A dispersion of polymer particles in molten wax is applied to cellulosic stock at a temperature below the melting point of the polymer. This treated cellulosic stock is then heated to a temperature above the melting point of the polymer and subjected to pressure. The resulting laminated product is polymer coated-wax impregnated cellulosic stock. The polymer used must be substantially insoluble in the molten wax at a temperature below the melting point of the polymer and must be fusible below a temperature which would degrade the stock. This product has utility as a packaging material comprising a high water vapor barrier coupled with a tough, scuff-resistant, nonblocking surface.

[ Feb. 12, 1974 METHOD OF PREPARING POLYMER COATED-WAX IMPREGNATEDCELLULOSIC STOCK [75] Inventors: lrl N. Duling, West Chester; John C.

Merges, Jr., Glen Mills, both of Pa.

[73] Assignee: Sun Research and Development Co.,

Philadelphia, Pa.

22 Filed: July 15, 1971 21 Appl.No.: 163,04l

Related US. Application Data [63] Continuation-impart of Ser. No.884,847, Dec. 15,

1969, abandoned, which is a continuation-in-part of Ser. No. 745,884,July 18, 1968, abandoned.

[52] US. Cl.'..... 117/155 UA, 117/65.2, 117/155 R,117/l57,1l7/158,1ll/168 [51] Int. Cl. D21h 1/28, D21h H36 [58] Field ofSearch.. 1l7/65.2, 92, 143 R, 155 UA, 1l7/158,168,155 R, 157

3,580,736 5/1971 Moyer et a1. 117/158 X 3,632,426 1/1972 Kohn et a1,117/158 3,653,958 4/1972 Kohn et al. 117/158 3,353,992 ll/l967 Grenleget al. l17/l38.8 3,558,542 l/l97l McDonald 260/27 3,577,373 5/1971Kremer et al 260/23 Primary Examiner-William D. Martin AssistantExaminer-M. R. Lusignan Attorney, Agent, or Fir mC1e0rge L. Church;Donald R. Johnson; Anthony Potts,J r.

[ ABSTRACT Porous cellulosic stock can be coated with a thermoplasticpolymer coating while being impregnated with a wax by this invention. Adispersion of polymer particles in molten wax is applied to cellulosicstock at a temperature below the melting point of the polymer. Thistreated cellulosic stock is then heated to a temperature above themelting point of the polymer and subjected to pressure. The resultinglaminated product is polymer coated-wax impregnated cellulosic stock.The polymer used must be substantially insoluble in the molten wax at atemperature below the melting point of the polymer and must be fusiblebelow a temperature which would degrade the stock. This product hasutility as a packaging material comprising a high water vapor barriercoupled with a tough, scuffresistant, non-blocking surface.

9 Claims, 2 Drawing Figures Pmmmrrmwn FIGURE l FIGURE 2 INVENTORS lRL N.ouume JOHN c. MERGES JR.

ATTORNEY METHOD OF PREPARING POLYMER COATED-WAX IMPREGNATED CELLULOSICSTOCK CROSS REFERENCE TO RELATED APPLICATIONS This application is acontinuation-in-part of our copending application Ser. No. 884,847;filed Dec. 15, 1969 nowabandoned, which was a continuation-inpart of ourcopending application Ser. No. 745,884, filed July 18, 1968, nowabandoned. Copending applications Ser. No. 884,879, now US. Pat. No.3,665,068, which relates to a method of forming porous objects ofpolyethylene having an extremely high molecular weight and Ser. No.885,355, now abandoned, which relates to a method of extruding extremelyhigh molecular weight polyolefins, are also continuations-in-part ofapplication Ser. No. 745,884. Both of these latter ap plications werefiled of even date with Ser. No. 884,847.

BACKGROUND OF THE INVENTION stock with a polymer which imparts a tough,scuff-' resistant, non-blocking surface to the stock. The method can beused to apply a polymer coating to one or both surfaces of the stock.

Coating paper with polyethylene particles having about a 300,000molecular weight asan aqueous dispersion was recently reported in TAPPI,December 1968, Vol. 51, No. 12, Paper Coating with PolyethyleneDispersion, L. R. Ridgeway et al., pages l29A-l- 32A. After an aqueousdispersion containing 60 percent polyethylene has been applied to kraftpaper the combination is heated to evaporate the water and fuse thepolymer particles. For food packaging paper requiring only a moderatedegree of moisture protection two separate applications of thedispersion are required.

The advantages of the present invention, compared to theheretoformentioned aqueous dispersion technique, are that no heat isrequired to evaporate water and an impregnation of the cellulosic stockwith wax occurs and imparts a high degree of impermeability to moisture.

SUMMARY OF THE INVENTION Porous cellulosic stock can be impregnated withwax and coated with a polymer by the method described herein. Thepolymer must be substantially insoluble in the molten wax at atemperature below the melting point of the polymer. A dispersion of thepolymer in molten wax, at a temperature below the melting point of thepolymer, is applied to the porous cellulosic stock. Afterwards, thetemperature of the applied coating is raised to above the melting pointof the polymer but below the degradation temperature of the stock andpressure is applied causing the melted polymer particles to form acontinuous polymer coating. The resulting wax impregnated cellulosicstock coated on one or both surfaces with a polymerhas utility aspackaging material with a high water vapor barrier. In addition thecoated surfaces are resistant to scuffing, are nonblocking and have aglossy attractive finish. Examples of thermoplastic polymers which canbe used with this invention are as follows: polyethylene with amolecular weight in excess of 1,000,000, polypropylene with a molecularweight in excess of 100,000, acrylonitrilebutadiene-styrene copolymerhereinafter referred to as ABS, polyacetal polyacrylic, cellulosicpolymer, ionomer polymer, methylpentene polymer, polyamide,polycarbonate, phenylene oxide polymer, polystyrene, unplasticizedpolyvinyl chloride, polyvinylidene chloride, and thermoplasticpolyester.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 schematically illustrates onemethod of applying the wax-polymer dispersion to cellulosic stock inaccordance with the invention.

FIG. 2 is a cross-sectional view of the finished laminated product.

DESCRIPTION A method of preparing polymer coated-wax impregnatedcellulosic stock according to this invention is illustrated in FIG. 1.Finely divided thermoplastic polymer and solid wax are placed in asuitable container 2. The temperature of the polymer and wax in thecontainer is raised to above the melting point of the wax but below themelting point of the polymer by a suitable heater 11. After the waxmelting sufficient agitation is applied by a conventional mixer 10 tokeep the finely divided polymer uniformly distributed throughout themolten wax. The dispersion in the container 2 is transferred, in thisillustration by gravity, to the cellulosic stock 1 in front of thedoctor blade 3. As soon as the dispersion contacts the stock absorptionof the wax in dispersion by the stock begins. The cellulosic stock 1moves on a smooth flat surface 4 towards the doctor blade 3. Thetemperature of the molten wax-polymer dispersion is maintained below themelting point of the polymer. The doctor blade 3 causes a predeterminedthickness of dispersion 12 to be deposited on the stock 1. The coveredstock, as indicated by 9, travels to a hot roll 5, where the highertemperature causes most of the remaining wax to be rapidly absorbed bythe stock and the polymer to melt while the pressure spreads the moltenparticles into one continuous coating. Afterwards the stock is cooled bycold roll 6 and rollers 7 move the finished product 8 away.

FIG. 2 is a cross-sectional view along section AA in FIG. 1 of thefinished product 8 prepared by the abovedescribed method. The substratelayer 22 represents the cellulosic stock 1 now impregnated with wax fromthe wax-polymer dispersion 12. The substrate layer 22 is covered with acontinuous polymer coating 21, the polymer being from the wax-polymerdispersion 12. Because most of the wax is absorbed by the stock 22 andthe polymer is substantially insoluble in the molten wax the continuouspolymer coating is substantially all polymer.

Since the fusion step in the coating operation results in a practicallyquantitative separation of the wax from the polymer, the barrierproperties of these coatings are those of the polymer film combined withthose of the wax-impregnated cellulosic stock. Thus, for example,dry-waxed paper is known to be a good barrier to moisture but a poor oneto water vapor or grease. Polymer films, although generally showingexcellent resistance to moisture, vary widely in their resistance toboth water vapor and grease. Thus, PVC will provide '7 Table I If athermoplastic polymer which is soluble in molten wax at a temperaturebelow the melting point of the polymer is used with this invention thefollowing problems arise. First if the polymer is soluble in the moltenwax at a temperature below the melting point of the polymer theviscosity of the resulting combination is drastically increased. Thisresulting high viscosity combination is very difficult to handle and toapply to the stock. Furthermore on coating the stock the combination isabsorbed by the stock. The remaining combination, after being heated toa temperature above the Wax Absorption Time of Various Cellulosic StocksTime required for a 0.1 ml. drop of wax to be absorbed into a test sheetat 160F.

These stocks are defined in THE DICTIONARY OF PAPER,

3rd Edition, American Paper and Pulp Association, 1965.

The data in Table I indicates that a coated stock such as coated oil cancardboard, having a wax absorption time of 6 to 10 minutes, would be astock which probably should not be used with this invention. However, acoated stock such as medium density freezer'carton, having a waxabsorption time of to 22.5 minutes, would be a stock which normallywould not be used with this invention.

The pulp used to make the various cellulosic stocks that can be used inthis invention can be derived from a suitable source such as wood,reclaimed paper, cotton fibers and other fibers such as manila hemp,jute,

etc.

Cellulosic stock also refers to wood and porous products made therefrom.Examples of such products are hardboard, particleboard, insulating boardand plywood. These boards are defined in ENCYLOPEDIA OF CHEMICALTECHNOLOGY, Kirk-Othmer, 2nd Edition, Vol. 21, Section Wallboard.

The wax used herein can be a petroleum wax obtained by any one of theprocesses described in Chapter 5 of THE CHEMISTRY AND TECHNOLOGY 0FWAXES by A. H. Warth, 2nd Edition and can be any one of the refined orunrefined petroleum waxes described in the same chapter. Synthetic waxesthat .can be used are described in Chapter 6 of the aforementionedreference. I

Petroleum wax is commercially available with a wide range of physicalproperties. Paraffin waxes are available with melting points from about126F. to 153F. (ASTM D87), oil contents from about 0.1 to about 1.2percent (ASTM D721 penetration at 77F. from about 9 to 40 (ASTM D1321),specific gravity at 212F. from about 0.756 to 0.767 (ASTM D287).Microcrystalline waxes are available with melting points from about151F. to 193F. (ASTM D127), oil contents from about 0.4 to about 1.5percent (ASTM D721), and specific gravity at 212F. from about 0.786 to0.795 (ASTM D287). While these different petroleum waxes will beabsorbed at different rates by various cellulosic stocks, our inventioncan be'used with any petroleum wax fraction that will be absorbed by thestock.

melting point of the polymer and having pressure applied, forms arelatively soft polymer-wax coating on the surface of the stock. Thus toavoid the heretoformentioned problems the thermoplastic polymers whichcan be used with this invention must be substantially insoluble in themolten wax at a temperature below the melting point of the polymer.

Examples of thermoplastic polymers which are substantially insoluble inthe molten wax at a temperature below the melting point of the polymerare as follows: polyethylene with a molecular weight in excess of1,000,000; polypropylene with a molecular weight in excess of 100,000,ABS, acetal, i.e., homopolymer and copolymer, acrylics, i.e., unmodifiedand modified, cellulosic, i.e., nitrate, acetate, propionate, butyrateand ethyl cellulose, ionomer, methylpentene polymer, polyamide, phenoxy,phenylene oxide, including the modified forms, polycarbonate,polystyrene, including copolymers of styrene-butadiene andstyreneacrylonitrile, unplastieized polyvinyl chloride which is alsoreferred to as rigid polyvinylchloride, polyvinylidene chloride andthermoplastic polyester. These thermoplastic polymers are defined as tochemicalcompositionfphysieal properties, aaimefiiaas of preparation inMODERN PLASTIC ENCYLOPEDIA, Vol. 47, 1970/1971. Generally, polyestersare classed as thermoset polymers; however, a few polyesters arethermoplastic. The latter requires heat to make it formable and aftercooling can be reheated and reformed into new shapes a number of timeswithout significant change in properties. A thermoset polymer uses heatto make its, shape permanent. After a thermoset is formed into permanentshape, usually with heat and pressure, it cannot be remelted orreformed. The aforementioned polyethylene, polypropylene, polyamide,cellulosic, polystyrene, polycarbonate, polyvinyl chloride and theacrylic are the preferable thermoplastic polymers.

The thermoplastic polymer used in this invention,

when added to the wax, is in the form of finely divided particles. Ifthe particles are too large, say passing through 3 mesh but remaining on20 mesh, the resulting dispersion is unstable in that theparticlessettle out rapidly causing problems during the' application of thedispersion to the stock. All'references to mesh herein refers to U. S.Sieve Series. Even if this settling problem can be overcome theresulting polymer coating on the stock is of non-uniform thickness andis not continuous; that is, there are some areas where there is nopolymer coating. Thus while this invention is operable if all thepolymer particles pass through a 20 mesh, it is preferable that allparticles pass through 100 mesh and even more preferable that allparticles pass through 200 mesh. Particle size distribution alsoinfluences dis persion stability and dispersion viscosity. At the samewax-polymer ratios a wide range particle distribution, compared to anarrow range particle distribution, tends to have a greater viscosityand hence greater stability. The limits as to particle size distributionrange can be easily determined by those skilled in the art.

The viscosity of the dispersion depends on the concentration of thepolymer in the wax, the affinity of the polymer for wax and particlesize and shape. For instance, a dispersion containing 60 weight percentof polymethylacrylate having particle size of 80/100 mesh, has the sameflow characteristics of a dispersion I containing 25 weight percent ofpolyethylene having a molecular weight of 2 million and particle size of100/200 mesh. Spherical particles, as formed insuspensionpolymerization, flow more readily than those irregularlyshaped, such as those resulting from grindmg.

The weight ratio of the polymer to the wax used in this inventiondepends on dispersion stability and dispersion viscosity which. in turndepends on polymer particle size and particle size distribution.Satisfactory weight ratios are 5 to 65 parts by weight of finely dividedpolymer and 35 to 95 parts by weight of wax; the preferable weightratios are to 55 parts by weight of finely divided polymer and 45 to 90parts by weight of wax.

The preliminary step in practicing this invention is to prepare thedispersion. The solid wax is placed in a suitable containerand heateduntil the wax becomes molten; but the resulting temperature should notexceed the melting point of the polymer being used. After the wax melts,the polymer is added; mildagitation is usually necessary to form thedispersion. Alternatively, both the solid wax and the polymer particlescan be placed in a container and heated together to a temperaturebelowthe polymers melting point. immediately after the dispersion hasbeen prepared it can be used or it can be cooled and the resulting solidused at a later time. The permissible temperature range used to preparethe dispersion depends on the melting point of the specific wax beingused and the melting point of the specific polymer being used.

The dispersion consisting of molten wax and polymer particles is appliedto the surface of a cellulosic stock as defined herein. The applicationofa uniformly thick layer of dispersion to the stock can be obtained byusing a doctor blade, or by extruding (curtain coating), or by a rollcoater or some other suitable equipment.

As soon as the dispersion touches the stock the wax starts to beabsorbed by the stock. The length of time during which this absorptionoccurs before the application of additional heat and pressure depends onthe equipment used, the wax absorption rate of the stock and the amountof wax applied per surface area of stock. This length of time can rangefrom almost zero to many minutes. An example where this length of timeis about zero is as follows. An extruded dispersion film containing arelatively small percentage of wax, contacts the stock just as the stockcomes in contact with a heated roller. This heated roller raises thetemperature of the dispersion above the fusion point of the polymer andapplies the desired pressure to the polymer coating. Thus substantiallyall the wax absorption by the stock occurs while the stock is in contactwith the heated roller. On the other hand where this length of time ismany minutes long is illustrated by this example. After the dispersioncontaining a relatively large percentage'of wax is applied, theadditional heat and pressure is not applied until substantially all thewax is absorbed by the stock. During this long intervening period thetemperature of the dispersion must be above the melting point of the waxbut below the melting point of the polymer. A minor amount of wax canremain unabsorbed so that the polymer particles remain evenlydistributed on the stock during movement of the stock.

After the application of the dispersion to the stock, the coated stockis subjected to additional heat to raise the temperature of dispersionto above the melting point of the polymer and subjected to pressure tocause the melted polymer particles to form the desired continuous smoothcoating. However, the maximum temperature of the dispersion cannotexceed a temperature which causes degradation of the stock. For paper,discoloration and/or loss of strength would be examples of degradationcaused by too high a temperature. Thus for paper stocks the maximumtemperature would be about 500 550F. This degradation temperaturelimitation means that certain thermoplastic polymers cannot be used withthe method defined herein because the polymers fusion point exceeds thedegradation temperature of the stock undergoing coating.

The application of this heat to raise the temperature of the dispersioncan precede the application of pressure by some finite time or can besimultaneous with the pressure. The amount of pressure applied dependson the type of polymer and ability of the stock to withstand the appliedpressure without undesirable deformation. During this step any waxremaining on the surface is absorbed by the stock.

Subsequently the stock can be allowed to cool or can be cooled bysuitable heat removal device. A cold roller would be one example.

The heretoformentioned description discusses only the application of thepolymer coating to one surface. In a similar manner a polymer coatingcould be applied to the other side of the cellulosic stock. In thisembodiment the amount of wax applied in the first treatment should notbe such that the stock becomes completely impregnated with wax. In otherwords during the application of the coating on the second side, thepartially wax-impregnated stock has to absorb at least most of mers.

The following examples illustrate this invention:

EXAMPLES To demonstrate that this method could be used with manythermoplastic polymers many satisfactory runs ner. An oven wasmaintained at 160T. In this oven was 10 a roll ofstock and severalinches away was a doctor blade set to apply 2 to 5 mils of dispersion.The stock moved from the mounted roll under the doctor blade and out ofthe oven. The molten wax-polymer dispercontact with a mirror-finishplate (ferrotype) and backed with a second plate to facilitate handling,and the composite was placed between the platens of a press. The platento be brought into immediate contact with the back side of the polishedplate was preheated to 300F., sufficient to fuse the polymer. Theplatens were closed loosely for a few seconds to heat the polished plateand the polymer particles. The pressure was then raised to about 300psi. and maintained for a short time (about 10 sec.). The pressure wasreleased. and the assembly was removed from the press and cooled toabout room temperature. The resulting prod uct had a smooth, brightpolymer surface and the porwssixas iq sa with W Table ll Polymers andheating Conditions Used to Prepare Treated Stock Melting Time for,seconds Solid Point, Fusion Run Polymers F. Temp., F. Preheat FusionCooling Mesh Size"" 1 Polyethylene 280 350-400 10 10- 60 20 gPolyethylene 400 Pol ro lene 180 375- l0-- 4 poll t r lie 240 300-350tot 200, 140/ +200 5 Polymethylmethacrylate 390 400 MZQ 6 Polyvinylchloride 270 325-375 20 7 Nylon 11 200 450 20 100 8 Nylon 11 400 9 Nylon12 400 10 Nylon 6 430 ll Polycarbonate 460 I0 15-20 60 l00 12 Celluloseacetate butyrate 300 350 13 Polyvinylidene 300 (a) 200 mesh size meansthat all particles passed through a 200 mesh screen; 140/ 200 mesh sizem a 140 mesh screen butwere retained on a 200 r n esh.

(h) cii'ifbiiirds'fl t mil; 61 lbs. per 1000 sq. n. (1;) Molecularweight of 1.25 million.

M) Medium impact.

(e) Contains 13 wt. aeetyl groups and 37% hutyl groups (0 Rigid. (g)Molecular weight of 600.000. (h) Molecular weight of 2.0 million. h

sion was applied to the cup board between the roll and the doctor blade.Thus as the cup board traveled under the doctor blade a predeterminedthickness of dispersion was applied. Note that the thickness must belimited to lay down no more wax component than can be absorbed by thecup board. In these examples as the cup board left the oven much of thewax was absorbed by the cup board because of the slowness at whichthestock moved.

The coated surface of the cup board was placed in To demonstrate thatthis method could be used to form various thicknesses of the polymercoatings on a eellulosic stock many additional runs were made as shownin the accompanying Table 111. These runs were made in an analogousmanner as that described for the data reported in Table 11; however, theweight of polymer in the dispersion used varied from to 60 percent..Also the data in Table 111 demonstrates that the amount of wax thatimpregnated the cellulosic stock can be varied substantially.

TABLE III Film and Wax Loading on 185 lb/ream. 1'7-Point TubstoekPolymer Thickness in of Solid dispersion, Loading, lb/l000 ft of Paperpolymer Polymer weight Total Wax Polymer film, mils Polypropylene 15.610.4 5.2 1.1 Polyethylene" 25 12.2 7.2 5.0 1.0 Polyethylene 35 16.5 11.05.5 1.0 Polystyrene 18.6 1 1.5 7.1 1.3 Polyvinylchloride"" 40 17.8 11.39.5 1.4 lolyvlnylchloridc 40 11.6 6.5 5.1 0.7 Polyvinylltlenc 35 15.116.4 9.4 lolymcthylmethucrylutc 60 2| .9 8.5 1.1.4 2.2 (.cllultme ueelulebutyrutc 19.2 10.8 8.4 1.3

(a) Molecular weight of 600,000. (b) Molecular weight of 1.4 million.(cll igid eans that all the particles passed through The petroleum waxused in these examples had the following inspections:

Specific gravity at 212F., ASTM D287 Other-uncoated stocks were treatedin a like manner and similar results were obtained.

To determine the relative performance of the treated cup board as a foodwrapping, a modified test for grease resistance of paper (TAPPI T454ts-66) was employed. The modification consisted of substituting peanutoil for the turpentine used in this TAPPI test procedure. Only thepolystyrene and polyethylene (Runs 1 and 3) were tested on the polymercoated side. With both products no stain appeared on the book was asatisfactory polystyrene coated, wax impregnated plywood.

An unsatisfactory run was made using a polyethylene with a molecularweight of 100,000. This polyethylene was substantially soluble in moltenwax. When 25 parts of this polyethylene was added to 75 parts of moltenwax a gel-type mixture formed. The viscosity of this gel was high andmade the gel difficult to handle and apply. When this gel was applied tocup board the mixture of wax and polymer was absorbed by the cup board.The product that resulted had a soft non-glossy, waxpolymer surface witha wax-polymer impregnated substrate.

The invention claimed is:

l. Met hod o f p reparing an article comprising a wax impregnated porouscellulosic stock having a polymer coating, which comprises: i

a. establishing a heterogeneous composite consisting essentially of athermoplastic polymer in finely dipaper lying underneath the testspecimen after 1,800 de form and molten wax, said polymer is seseconds.This is the maximum test time. lected from the group consisting of:polyethylene Additional performance tests were conducted on with amolecular weight in excess of l ,0 00,000, polyvinyl chloride coated 17point tubstock and polyp lypropylene with a molecular weight in excessof styrene coated 17 point tubstock. The results of these 100,000,acrylonitrilebutadiene-styrene copolytests are shown in the accompanyingTable IV. mer, polyacetal, polyacrylic, cellulosic polymer, The glossdeveloped by fusion of the polymer against ionomer polymer, methylpentene polymer, polypolished surfaces was high in most cases.Polystyrene amide, phenylene oxide polymer, polycarbonate, and polyvinylchloride, as seen in Table IV, and other polystyrene, rigidpolyvinylchloride, polyvinylipolymers that vary in structure from thewax vehicle, dene chloride and thermoplastic polyester; displayexcellent gloss and gloss retention. Polyethylb. applying a coating ofsaid heterogenous composite ene and polypropylene tended to retain asmall amount to a porous cellulosic substrate at a temperature of waxwhich subsequently bloomed to the surface and above the melting point ofthe wax but below the thus reduced gloss. Polycarbonate andpolymethylmelting point of the polymer; the amount of coatmethacrylatefilms reflected 90 percent of incident ing being regulated so that atleast most of the wax light (black glass standard 100 percent) evenafter therein is absorbable in cellulosic substrate; several days ofaging. The high blocking temperature, c. heating said coating to atemperature between the 170F., and excellent scuff resistance reflectthe natmelting point of the polymer and the degradation ural surfaceproperties of the polymer films. temperature of the substrate andapplying pressure TABLE IV Performance of Dispersion-Coated TubstockRigid Polyvinyl chloride Polystyrene Loading Loading Film FilmPerformance Wax thickness Performance Wax thickness Characteristiclb/ream mils Characteristic lb/ream mils Water vapor permeability,

TAPPIT 464 2.31 53 1.3 2.16 31 1.2 Grease resistance, see 1800+ 46 0.81800+ 34 1.2 Gloss, reflected Initial 76 22 2.7 78 17 1.2 Aged, 24 yr.78 78 Block'irTg te inp.,"F. 170 35 1 7 170 33 1.0 Scuff resistanceExcellent Excellent Sealing strength At 73F Tear Tear At lF Tear Tear(a) Approximately 1 in. diam. pool of dyed peanut oil deposited onsurface: time to penetrate and stain paper underneath.

(b) Determined with Photovolt Glossmeter, angle 75'' from normal. Blackglass reflection.

(c) Weighting conformed to TAPILILQZ; in pvenat l70iF, 17 l 1 M A 56inch thick, three ply indoor plywood was treated in an analogous methodas described for the runs in Table 11. The dispersion container 40weight percent of polystyrene, fusion temperature was 300F. and theapplied pressure about 275 p.s.i. The resulting produce thereto to forma continuous molten polymer layer on the surface of the poroussubstrate;

(1. and thereafter cooling the resultant article.

Me h s or iin .t a re n seiltsts geneous composite contains Sto 65 partsby weight of finely divided polymer and 35 to 95 parts by weight of saidwax.

3. Method according to claim 1 wherein all the finely divided polymer isfiner than 100 mesh.

4. Method according to claim 1 wherein all the finely divided polymer isfiner than 200 mesh.

5. Method according to'claim 1 wherein the wax is a petroleum wax.

6. Method according to claim 5 wherein heterogeneous composite contains5 to 65 parts by weight of finely divided polymer, said polymer beingfiner than 100 mesh. 7

7. Method according to claim 1 wherein the heterogeneous compositecontains 5 to 65 parts by weight of finely divided polymer, said polymerbeing finerthan 100 mesh, and the wax is a petroleum wax.

8. Method according to claim 7 wherein the thermoplastic polymer isselected from the group consisting of: polyethylene with a molecularweight in excess of 1,000,000, polypropylene with a molecular weight inexcess of 100,000, polyamide, cellulosic, polystyrene, polycarbonate,rigid polyvinylchloride and acrylic.

9. Method according to claim 8 wherein said heterogeneous compositecontains 10 to 55 parts by weight of finely divided polymer and to 90parts by weight of wax.

2. Method according to claim 1 wherein said heterogeneous compositecontains 5 to 65 parts by weight of finely divided polymer and 35 to 95parts by weight of said wax.
 3. Method according to claim 1 wherein allthe finely divided polymer is finer than 100 mesh.
 4. Method accordingto claim 1 wherein all the finely divided polymer is finer than 200mesh.
 5. Method according to claim 1 wherein the wax is a petroleum wax.6. Method according to claim 5 wherein heterogeneous composite contains5 to 65 parts by weight of finely divided polymer, said polymer beingfiner than 100 mesh.
 7. Method according to claim 1 wherein theheterogeneous composite contains 5 to 65 parts by weight of finelydivided polymer, said polymer being finer than 100 mesh, and the wax isa petroleum wax.
 8. Method according to claim 7 wherein thethermoplastic polymer is selected from the group consisting of:polyethylene with a molecular weight in excess of 1,000,000,polypropylene with a molecular weight in excess of 100,000, polyamide,cellulosic, polystyrene, polycarbonate, rigid polyvinylchloride andacrylic.
 9. Method according to claim 8 wherein said heterogeneouscomposite contains 10 to 55 parts by weight of finely divided polymerand 35 to 90 parts by weight of wax.